Printing system

ABSTRACT

In a printing system  10  connected to a host computer  20  as an upper system via a serial bus, communication control information used in a shift from a power saving mode to a normal transfer mode are previously in a response controlling portion  147  before a CPU  151  in a printing controlling portion  12  is shifted into the power saving mode, and then the response controlling portion  147  can receive the data based on the set communication control information without intervention of a CPU  151  in the cancel of the power saving mode.

BACKGROUND OF THE INVENTION

[0001] 1. [Technical Field]

[0002] The present invention relates to a printing system for receivingprint data transmitted from an upper system to execute a printingprocess and, more particularly, a printing system having a power-savingmode that can save the power (energy) by stopping the power source andthe clock supplied to a printing portion, a controlling portion, etc. inthe standby state in which no printing process is executed.

[0003] 2. [Related Art]

[0004] In the prior art, as the system of this type, it has been wellknown the system employing the system that the power supply of thesystem is turned ON while asserting the first output control signal(busy signal) when the receiving operation is started in thepower-saving mode, and then the busy signal is negated when theinitialization is completed (see Patent Application Publication (KOKAI)Hei 10-56526, for example). In other words, the receiving operation fromthe parallel interface is stopped once by asserting the busy signal, andthen the receiving operation is started again by negating the busysignal at the stage when the receiving preparation is completed byturning ON the power supply of the system.

[0005] [Problems to be Solved]

[0006] However, in the above prior art, first the CPU of the controllingportion for controlling the overall system executes the building-upprocess at the time of returning from the power-saving mode, and thenthe operation is shifted to the receiving operation. For this reason, itmay be considered such a situation that, if a time required for abuilding-up process of CPU is long, a return time from the power-savingmode to the normal mode (normal transfer mode) exceeds a time-out timeof the data transmission on the upper system side, e.g., the hostcomputer side, to thus cause the transmission error.

[0007] At that time, since the process to transmit the data once again,to interrupt temporarily the transmission, or the like is carried out onthe host computer side, there is the problem that the data transferefficiency is extremely lowered. Also, according to this, there is thepossibility that a time required to start the printing when thereceiving operation is started in the power-saving mode, i.e., FPOT(First Print Out Time) is increased extremely.

SUMMARY OF THE INVENTION

[0008] The present invention has been made in view of the abovesubjects, and it is an object of the present invention to provide aprinting system capable of avoiding the generation of the time-out erroron the upper system side and also enabling the optimization of FPOT, inshifting the mode from the power-saving mode to the normal mode evenwhen a time required for a building-up process of CPU is long.

[0009] [Means for Solving the Problems]

[0010] A printing system of the present invention including a printingportion and a controlling portion for controlling the printing portion,and having a power saving mode for stopping a supply of a power sourceto at least the controlling portion, the printing system comprising adeciding portion for deciding a shift from a normal mode to the powersaving mode, a setting portion for setting communication controlinformation used in the shift from the power saving mode to the normalmode after the shift to the power saving mode is decided by the decidingportion, and a receiving portion for receiving data based on thecommunication control information set by the setting portion in theshift from the power saving mode to the normal mode not to use thecontrolling portion.

[0011] In the printing system having the above configuration, when theshift from the normal mode to the power saving mode is decided by thedeciding portion, the setting portion sets the communication controlinformation used in the shift from the power saving mode to the normalmode in response to this. Then, the receiving portion can receive thedata based on the communication control information previously set bythe setting portion without the intervention of the controlling portionin the shift from the power saving mode to the normal mode.

[0012] A printing system of the present invention including a printingportion and a controlling portion for controlling the printing portion,and having a power saving mode for stopping a supply of a power sourceto at least the controlling portion, the printing system comprising astoring portion for storing received data, a deciding portion fordeciding a receiving speed based on a returning time from the powersaving mode to a normal mode and a capacity of the storing portion, anda receiving portion for receiving data based on the receiving speeddecided by the deciding portion in a shift from the power saving mode tothe normal mode to store the data in the storing portion.

[0013] In the printing system having the above configuration, first thedeciding portion decides the receiving speed of the data based on thereturning time from the power saving mode and the capacity of thestoring portion. Then, in the shift from the power saving mode to thenormal mode, the receiving portion receives the data based on thereceiving speed previously decided by the deciding portion and thenstores the received data in the storing portion.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1 is a block diagram showing an outline of a configuration ofa printing system according to a first embodiment of the presentinvention.

[0015]FIG. 2 is a flowchart for explaining an operation of the printingsystem according to the first embodiment.

[0016]FIG. 3 are views showing an example of a relationship between acommunication time between a host computer and a print controllingportion and a buffer storing amount every mode respectively.

[0017]FIG. 4 is a block diagram showing an outline of a configuration ofa printing system according to a second embodiment of the presentinvention.

[0018]FIG. 5 is a flowchart for explaining an operation of the printingsystem according to the second embodiment.

[0019]FIG. 6 is a timing chart showing a basic handshake of a parallelinterface.

[0020]FIG. 7 is a view showing an example of a relationship between areceived-data buffer empty capacity and a busy assert period.

[0021]FIG. 8 is a transition timing chart from a compatible mode to anegotiation phase of a parallel interface based on IEEE1284.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] [Embodiments of the Invention]

[0023] Embodiments of the present invention will be explained in detailwith reference to the drawings hereinafter.

[0024] (First Embodiment)

[0025] FIG.1 is a block diagram showing an outline of a configuration ofa printing system according to a first embodiment of the presentinvention. In FIG.1, a printing system 10 of the present embodiment isconstructed such that such printing system comprises a printing portion11, a print controlling portion 12 for controlling the printing portion11, and a main power supply portion 13, and is connected to a hostcomputer 20 as an upper system, for example, via a serial bus 30 totransmit/receive the serial data to/from the host computer 20.

[0026] The print controlling portion 12 is constructed such that suchprint controlling portion has a communication I/F (interface) 14 forexecuting the communication with the host computer 20 via a serial bus30, and a controlling portion 15 for controlling the overall presentsystem, and the power source is directly supplied from the main powersupply portion 13 to the communication I/F (interface) 14, and also thepower source is selectively supplied to the printing portion 11 and thecontrolling portion 15 via a power supply switch 16.

[0027] In this print controlling portion 12, the communication I/F 14has a configuration that has a serial/parallel I/F 141, a command/dataanalyzing portion 142, a data payload controlling portion 143, apower-saving controlling portion 144, a buffer storing portion 145, adata-storing controlling portion 146, and a response controlling portion147. In this communication I/F 14, the serial/parallel I/F 141 executesan action to convert the serial data received from the host computer 20into the parallel data and also convert the parallel data processed inown device into the serial data.

[0028] The command/data analyzing portion 142 analyzes the command inthe data received from the host computer 20 and the data contents. As anexample, this command/data analyzing portion 142 executes the decisionwhether or not the data is directed to own device, by looking up theaddress area in the packet. Where the packet signifies the unit in whichthe information are arranged to have a predetermined size. Then, thedata block to be transmitted, i.e., the frame is constructed by sets ofthe packets (packet group)

[0029] The data payload controlling portion 143 controls the datapayload from the host computer 20 per one packet. The power-savingcontrolling portion 144 issues appropriately a power-saving mode shiftauthorization response signal for permitting the shift from the normaltransfer mode (normal mode) to the power-saving mode, a power-savingmode cancel informing signal, and an interrupt informing signal to theCPU 151.

[0030] The data received from the host computer 20 are stored in thebuffer storing portion 145 under the control of the data-storingcontrolling portion 146. The communication control informationindicating what response should be made to the data received from thehost computer 20 in the shift from the power-saving mode to the normaltransfer mode are set previously in the response controlling portion 147under the control of the CPU 151.

[0031] Here, as the communication control information, for example,there may be listed the information as to a predictive time requireduntil the process in the print controlling portion 12 can be startedafter the CPU 151 returns from the power-saving mode to the normaltransfer mode and completes the boot process, a storing amount(capacity) of the buffer storing portion 145, the maximum data payloadform the host computer 20 per one packet, a reply rates of the ACKresponse and the NAK response to the data received from the hostcomputer 20, etc. These communication control information may be setarbitrarily.

[0032] The controlling portion 15 is constructed such that suchcontrolling portion has the CPU 151, a RAM 152, a ROM 153, a DMAC 154for executing the DMAC (Direct Memory Access Controller) transfer, and apower supply controlling portion 155, and is connected mutually to thecommunication I/F 14 via the parallel bus 17. In this controllingportion 15, the DMAC 154 issues a DMA transfer authorization signal tothe data-storing controlling portion 146 when the CPU 151 completes theboot process.

[0033] The power supply controlling portion 155 is provided to controlON(close)/OFF(open) of the power supply switch 16 that supplies/stopsthe power supply voltage to the printing portion 11 and the controllingportion 15. The power supply controlling portion 155 stops the powersource to the printing portion 11 and the controlling portion 15 byturning OFF the power supply switch 16 in response to this when thepower-saving mode shift authorization response signal is issued from thepower-saving controlling portion 144, and also supplies the power sourceto the printing portion 11 and the controlling portion 15 by turning ONthe power supply switch 16 in response to this when the power-savingmode cancel informing signal issued from the power-saving controllingportion 144.

[0034] Next, an operation of the printing system 10 having the aboveconfiguration according to the first embodiment will be explained incompliance with a flowchart in FIG.2 hereunder. Here, controllingprocedures in the shift from the normal transfer mode to thepower-saving mode and then to the normal transfer mode in response tothe power-saving mode canceling information will be explained.

[0035] In the state that the normal transfer mode is set (step S101),when the print controlling portion 12 is not receiving the dataaddressed to own system from the host computer 20, such printcontrolling portion 12 monitors the request for the shift to thepower-saving mode issued from the CPU 151 (the issue of the power-savingmode shift authorizing response signal) (step S102). The CPU 151 setspreviously the communication control information, that indicates whatresponse should be made to the data received from the host computer 20in the shift from the power-saving mode to the normal transfer mode, inthe response controlling portion 147 (step S103).

[0036] When the setting of the communication control information to theresponse controlling portion 147 is completed under the control of theCPU 151 (step S104), the power-saving controlling portion 144 issues thepower-saving mode shift authorization response signal to the powersupply controlling portion 155 (step S105). When the power supplycontrolling portion 155 receives the power-saving mode shiftauthorization response signal, it stops the power source supply to theprinting portion 11 and the controlling portion 15, i.e., the CPU 151,the RAM 152, the ROM 153, and the DMAC 154, by turning OFF the powersupply switch 16. As a result, the operation mode is shifted to thepower-saving mode.

[0037] In the power-saving mode, the serial/parallel I/F 141 and thecommand/data analyzing portion 142 always monitor the contents of thedata from the host computer 20, i.e., whether or not the data addressedto own system is detected (step S106). The data addressed to own systemis decided by looking up the address area in the packet. If theserial/parallel I/F 141 and the command/data analyzing portion 142receive the data addressed to own system from the host computer 20, thepower-saving controlling portion 144 issues the power-saving mode cancelinforming signal to the power supply controlling portion 155 and alsoissues the interrupt informing signal to the CPU 151 in response to this(step S107).

[0038] When the power supply controlling portion 155 receives thepower-saving mode cancel informing signal, it starts the power sourcesupply to the printing portion 11 and the controlling portion 15 byturning ON the power supply switch 16. When the power supply is suppliedto the CPU 151, first this CPU 151 executes the boot process. During theboot process of the CPU 151, the response controlling portion 147executes the communication with the host computer 20 in accordance withthe communication control information stored therein (step S108). Also,the response controlling portion 147 monitors the reception of the DMAtransfer authorization signal from the DMAC 154 (step S109). In thiscase, the details of the setting operation of the communication controlinformation will be described later.

[0039] When the CPU 151 finishes the boot process, the DMAC 154 issuesthe DMA transfer authorization signal to the data-storing controllingportion 146 in response to this. When the data-storing controllingportion 146 receives the DMA transfer authorization signal from the DMAC154, it starts the transmission of the DMA data onto the parallel bus 17(step S110). Also, the CPU 151 issues the power-saving mode cancelinforming signal to the power-saving controlling portion 144 and shiftsto the normal transfer mode (step S111)

[0040] Then, it will be explained hereunder at what mode thecommunication control is executed between the host computer 20 as theupper system and the print controlling portion 12 based on thecommunication control information at the time of return from thepower-saving mode to the normal transfer mode.

[0041] FIG.3 shows an example of a relationship between a communicationtime between the host computer 20 and the print controlling portion 12during the communication in communication controlling modes based on thecommunication control information, i.e., mode A, mode B, mode C, andmode D, and an amount of data stored in the buffer storing portion 145,respectively.

[0042] As described above, the communication control informationindicate a predictive time T0 required until the process in the printcontrolling portion 12 can be started after the CPU 151 returns from thepower-saving mode to the normal transfer mode and complete the bootprocess, a storing amount of the buffer storing portion 145 (referredsimply to as a “buffer storing amount” hereinafter), the maximum datapayload form the host computer 20 per one packet, reply rates of the ACKresponse and the NAK response to the data received from the hostcomputer 20, etc.

[0043] In the mode A in FIG.3, when a time comes up to the predictivetime T0 required until the process in the print controlling portion 12can be started after the CPU 151 returns from the power-saving mode andcompletes the boot process, the buffer storing amount is small. Thecommunication control in this mode A can be implemented by setting loweither the maximum data payload form the host computer 20 per one packetor the reply rates of the ACK response and the NAK response to the datareceived from the host computer 20, in order to lower the predictivetime T0 required until the process in the print controlling portion 12can be started after the CPU 151 returns from the power-saving mode andcompletes the boot process and the receiving speed.

[0044] At this time, the maximum data payload and the reply rates of theACK response and the NAK response to the received data may be lowered atthe same time. The communication control in this mode A is suitable forthe communication that has the relatively low emergency, like the caseswhere the process in the print controlling portion 12 cannot be startedbecause other process is started after the CPU 151 returns from thepower-saving mode and completes the boot process, etc.

[0045] In the mode B in FIG.3, when the time reaches the predictive timeT0 required until the process in the print controlling portion 12 can bestarted after the CPU 151 returns from the power-saving mode andcompletes the boot process, the buffer storing amount is large. Thecommunication control in this mode B can be implemented by setting higheither the maximum data payload from the host computer 20 per one packetor the reply rates of the ACK response and the NAK response to the datareceived from the host computer 20, in order to increase the predictivetime T0 required until the process in the print controlling portion 12can be started after the CPU 151 returns from the power-saving mode tocomplete the boot process, and the receiving speed.

[0046] At this time, the maximun data payload and the replay rates ofthe ACK response and the NAK response to the received data may be sethigher at the same time. The communication control in this mode B issuitable for the communication that has the relatively high emergency,like the cases where the process in the print controlling portion 12 canbe started immediately because other process is not started after theCPU 151 returns from the power-saving mode and completes the bootprocess, etc.

[0047] In the mode C in FIG. 3, the predictive time T0 required untilthe process in the print controlling portion 12 can be started after theCPU 151 returns from the power-saving mode to complete the boot process,and a buffer storing amount set value Co are set. Then, such acommunication control is carried out that the print data is receivednormally before the buffer storing amount reaches the buffer storingamount set value Co while an amount of the received data is reduced intoa predetermined level after the buffer storing amount has reached thebuffer storing amount set value Co.

[0048] In the mode D in FIG. 3, the predictive time T0 required untilthe process in the print controlling portion 12 can be started after theCPU 151 returns from the power-saving mode to complete the boot process,and a buffer storing amount set value Co are also set. Then, such acommunication control is carried out that the print data is receivednormally before the buffer storing amount reaches the buffer storingamount set value Co while an amount of the received data is reducedgradually after the buffer storing amount has reached the buffer storingamount set value Co.

[0049] The communication control in the mode C and the mode D can beimplemented by setting high either the maximum data payload from thehost computer 20 per one packet or the reply rates of the ACK responseand the NAK response to the data received from the host computer 20, inorder to increase the buffer storing amount set value Co, that acts as aswitching point to switch the predictive time T0 required until theprocess in the print controlling portion 12 can be started after the CPU151 returns from the power-saving mode and completes the boot processand the receiving speed, and the receiving speed.

[0050] At this time, the maximum data payload and the reply rates of theACK response and the NAK response to the received data may be increasedsimultaneously. The communication control in the mode C and the mode Dis suitable for the communication that has the relatively highemergency, like the cases where the ordinary data receiving speed is notreduced as much as possible and also the process in the printcontrolling portion 12 can be started immediately because other processis not started after the CPU 151 returns from the power-saving mode andcompletes the boot process, etc.

[0051] As for the set values in the above communication controlinformation, a predetermined value may be set every time when the CPU151 shifts to the power-saving mode, otherwise a variable value may beset in response to the history made prior to the shift to thepower-saving mode, etc. when the CPU 151 shifts to the power-savingmode.

[0052] In this case, although the explanation is omitted from theflowchart in FIG. 2, it is needless to say that the print controllingportion 12 of the printing system 10 operates while always monitoringthe information of the suspend command and the resume command from thehost computer 20.

[0053] As described above, in the printing system 10 connected to thehost computer 20 as the upper system via the serial bus, thecommunication control information used in the shift from thepower-saving mode to the normal transfer mode are set previously in theresponse controlling portion 147 before the CPU 151 in the printcontrolling portion 12 shifts to the power-saving mode, and then theresponse controlling portion 147 executes the datatransmission/reception based on the set communication controlinformation in the cancel of the power-saving mode. As a result, afterthe cancel of the power-saving mode, the normal communication with thehost computer 20 can be carried out continuously without theintervention of the CPU 151. In other words, the CPU 151 executespreferentially the boot process immediately after the cancel of thepower-saving mode, but the communication with the upper system can becarried out during this processing period.

[0054] Also, if the information are transmitted from the host computer20 to the printing system 10, it is decided whether or not theinformation is addressed to own system by referring to the address areain the packet, and then the CPU 151 is started by informing thepower-saving controlling portion 144 in the print controlling portion 12of the interruption only when the information is addressed to ownsystem. Therefore, the start of the CPU 151 can be executed speedy andreduced to the lowest minimum.

[0055] In addition, the receiving speed of the data from the hostcomputer 20 is decided based on the return time from the power-savingmode to the normal transfer mode and the buffer storing amount, then thedata are received based on this decided receiving speed at the time ofreturn, and then the data are stored in the buffer storing portion 145under the control of the data-storing controlling portion 146.Therefore, the receiving speed can be set on the host computer 20 sidenot to generate the host time-out error. As a result, after the cancelof the power-saving mode, the generation of the time-out error in thehost computer can be prevented without the intervention of the CPU 151,and thus the flexible communication control can be carried out.

[0056] (Second Embodiment)

[0057]FIG. 4 is a block diagram showing an outline of a configuration ofa printing system according to a second embodiment of the presentinvention. In FIG. 4, a printing system 50 according to the presentembodiment is constructed such that such printing system comprises aprinting portion 51, a print controlling portion 52, a main power supplyportion 53, and a power supply controlling portion 54, and is connectedto a host computer 60 as the upper system, for example, via a parallelbus 70 to transmit/receive the parallel data to/from the host computer60.

[0058] The print controlling portion 52 is constructed such that suchprint controlling portion has a communication I/F 55 for executing thecommunication with the host computer 60 via a parallel bus 70, and acontrolling portion 56 for controlling the overall present system, andthe power source is directly supplied from the main power supply portion53 to the communication I/F 55, and also the power source is selectivelysupplied to the printing portion 51 and the controlling portion 56 via apower supply switch 57.

[0059] In this print controlling portion 52, the communication I/F 55 isconstructed to have a 1284 interface 551, a REQ controlling portion 552,a DMAC 553, and a timer 554 and to respond to various communicationstandards. The 1284 interface 551 consists of a 1284 controlling portion555 and a FIFO (first-in first-out) controlling portion 556, andexecutes the communication control based on IEEE (The Institute ofElectrical and Electronics Engineers, Inc.) 1284 standard that canachieve the illustrated high-speed parallel transfer, for example.

[0060] The communication interface is not limited to the 1284 interface551, and the USB (Universal Serial Bus) interface, the LAN (Local AreaNetwork) interface (100BT interface), etc. may be employed. Also, thesystem in which the interface is connected simultaneously to the uppersystem, i.e., the host computer 60, may be employed.

[0061] In the situation that the HALT (halt) state signal output fromthe CPU 561 in the controlling portion 56 indicates the normal transfermode, when the data transfer requesting signal is output from the 1284interface 551, the REQ controlling portion 552 outputs the data transferrequesting signal to the DMAC 553. The DMAC 553 executes the DMAtransfer in response to this data transfer requesting signal. The timer554 monitors the DMA transfer requesting signal output from the DMAC553, then counts a negate period of the DMA transfer request, i.e., aperiod during when the DMA transfer requesting signal is not output, andthen outputs a time-out interrupt signal to the CPU 561 when this countvalue comes up to a predetermined value that is decided previously.

[0062] The controlling portion 56 is constructed such that suchcontrolling portion has the CPU 561, a RAM 562, a ROM 563, and a bridgeimage processing portion 564, and the bridge image processing portion564 is connected mutually to the printing portion 51, the power supplycontrolling portion 54, and the communication I/F 55 via an internal bus58. The program executed in the CPU 561, etc. are stored in the ROM 563.The clock is supplied to the power supply controlling portion 54 from anoscillator (not shown), and also the receiving interrupt signal is inputinto the power supply controlling portion 54 from the communication I/F55. The power supply controlling portion 54 supplies the clock suppliedfrom the oscillator as it is to the CPU 561 and the bridge imageprocessing portion 564 in the controlling portion 56 or supplies themasked clock to them.

[0063] In the printing system 50 having the above configurationaccording to the second embodiment, the transmission data from the hostcomputer 60 as the upper system is input into the DMAC 553 via the 1284interface 551. When the DMAC 553 receives the reception data, ittransmits the DMA transfer requesting signal to the bridge imageprocessing portion 564 via the internal bus 58 and also outputs theinput data onto the internal bus 58. The data being output onto theinternal bus 58 is transferred to the RAM 562 as a main memory via thebridge image processing portion 564. The data being DMA-transferred tothe RAM 562 is subjected to the image process by the CPU 561, and thenoutput to the printing portion 51 via the bridge image processingportion 564.

[0064] Then, an operation in shifting the mode from the power-savingmode to the normal transfer mode will be explained in compliance with aflowchart in FIG. 5 hereunder.

[0065] First, when the power supply of the printing system 50 is turnedON, the power supply controlling portion 54 supplies the power source tothe controlling portion 56 and enters into the normal transfer mode(step S201). In this normal transfer mode, when the data reception isstarted via the 1284 interface 551, the DMA transfer is carried out bythe above operation. When the data reception is completed but thesubsequent data is not received, the timer 554 is started. If thesubsequent DMA transfer requesting signal is not asserted within apredetermined time, i.e., if the DMA transfer is not carried out betweenthe DMAC 553 and the RAM 562 for the predetermined time, a time-outinterrupt signal is output from the timer 554 to the CPU 561 (step S202)

[0066] When the CPU 561 receives the time-out interrupt signal, such CPU561 sets the communication control information used in the shift fromthe power-saving mode to the normal transfer mode (referred to as a“receiving mode/parameter” hereinafter) in the 1284 controlling portion555 in the 1284 interface 551, and also informs the REQ controllingportion 552 of the effect that the controlling portion 56 is shiftedinto the power-saving mode and thus the DMA transfer cannot be executed,and negates the data requesting signal to the DMAC 553 (step S203).

[0067] Then, the CPU 561 outputs the power supply OFF informing signalto the power supply controlling portion 54 via the bridge imageprocessing portion 564 such that the power source supply to thecontrolling portion 56 can be stopped. Then, the power supplycontrolling portion 54 turns OFF (opens) the power supply switch 57 inresponse to the power supply OFF informing signal. Accordingly, thepower supply to the controlling portion 56 is stopped and the system isshifted into the power-saving mode (step S204) At this time, the powersupply is still supplied continuously to the communication I/F 55.

[0068] The shift from the power-saving mode to the normal transfer modeis carried out according to following procedures. In other words, whenthe 1284 controlling portion 555 in the 1284 interface 551 received thedata after this data is transmitted from the host computer 60, such 1284controlling portion 555 detects a change in the input control signal (aleading edge of the strobe signal) (step S205) and asserts the receptioninterrupt-signal to the power supply controlling portion 54 (step S206).At this time, the power supply controlling portion 54 receives thisreception interrupt signal to turn ON the power supply switch 57.Accordingly, the power source supply to the controlling portion 56 isstarted again, and the CPU 561 starts the boot process (building-upprocess).

[0069] The CPU 561 outputs a return informing signal to the REQcontrolling portion 552 when the boot process is completed (step S207)and sets the normal transfer mode in the 1284 controlling portion 555 inthe 1284 interface 551. Thus, the DMA transfer is restarted. Moreparticularly, the REQ controlling portion 552 receives the returninforming signal from the CPU 561 and asserts the data requesting signalto the DMAC 553. In response to this, the DMAC 553 adjusts the DMAtransfer requests from other modules and requests the acquirement of theinternal bus 58 by outputting the DMA transfer requesting signal to theCPU 561 (step S208).

[0070] Then, when the DMAC 553 can acquire the internal bus 58, itoutputs the ACK signal to the FIFO controlling portion 556 in the 1284interface 551 and also outputs the DMA transfer requesting signal to thetimer 554 (step S209). Thus, the timer 554 is reset. Also, the FIFOcontrolling portion 556 receives the ACK signal and outputs the storeddata to the DMAC 553. Accordingly, the DMA transfer is carried outbetween the DMAC 553 and the RAM 562. That is, the mode is shifted intothe normal transfer mode (step S210).

[0071] In a series of above procedures, the case of the power-savingmode where the power supply controlling portion 54 stops the powersource supply to the controlling portion 56 is described as an example.In the case of the power-saving mode (sleep mode) where the power supplycontrolling portion 54 also stops the clock supply to the controllingportion 56, the process can be carried out in compliance with thesimilar procedures.

[0072] In this case, in setting the receiving mode/parameter in theabove power-saving mode, the lowest receiving data buffer capacity isreserved as the system based on the previously decided returning timefrom the power-saving mode to the normal transfer mode in the presentprinting system 50 and the time-out setting time of the host system. Ifthe storing buffers (memories) are present in the FIFO controllingportion 556 and the 1284 controlling portion 555, the receiving databuffer capacity used herein is given as a sum of both buffer capacities.

[0073] The data reception to meet the return time can be carried outwithout fail by using the reception parameter (receiving speed) setherein. More particularly, a busy assert period shown in FIG. 6 isadjusted in the parallel interface based on 1284. The assert time can beimplemented relatively easily if it is set constant by the register, asdescribed above.

[0074] In addition, as shown in FIG. 7, the assert time can be decideddynamically from a residual amount of the received-data buffer capacity.Accordingly, in the transition period from the power saving mode to thenormal transfer mode, the busy signal is asserted per one data receptionfor a time set by the 1284 controlling portion 555. Therefore, if thereception (handshake) is continued at the data receiving speed that isbelow the time-out period of the host system until a time required toreturn from the power saving mode has lapsed, the state that thereceived-data buffer capacity is filled to assert busy can be avoided.

[0075] Also, since the shift from the power saving mode to the normaltransfer mode, i.e., the decision of the cancel of the power saving modeis started by detecting the change of the input control signal in theparallel interface (leading edge of the strobe signal), the power savingmode can be canceled to respond the inquiry immediately when theinquiry, i.e., the transmission request, is issued from the upper system(host computer 60) to the present printing system 50 in the power savingmode. As shown in FIG. 8, this is because the strobe signal is changedin a negotiation phase based on IEEE1284 standard and thus the interruptsignal can be asserted by the above edge detecting portion.

[0076] As described above, in the printing system 50 connected to thehost computer 60 as the upper system via the parallel bus, the data canbe received based on the previously-set communication controlinformation without the CPU 561 immediately after the shift from thepower saving mode to the normal transfer mode. Therefore, it is possibleto receive the data within the returning time from the power saving modenot to generate the time-out error in the upper system side. As aresult, the mode can be returned to the normal transfer mode not tolower extremely the data transfer efficiency. That is, the FPOT that ismost suitable for the present printing system 50 can obtained.

[0077] In addition, since the decision of the cancel of the power savingmode is made by detecting the change of the input control signal line inthe parallel interface, the mode can be shifted into the normal transfermode by immediately canceling the power saving mode even when not onlythe data is to be received but also the inquiry, i.e., the transmissionrequest, is issued from the upper system (host computer 60) to thepresent printing system 50 in the power saving mode.

[0078] [Effects of the Invention]

[0079] As described above, according to the present invention, in theshift from the power-saving mode to the normal mode, the generation oftime-out error on the upper system side can be avoided and also the FPOTcan be optimized.

What is claimed is:
 1. A printing system comprising: a printing portion,a controlling portion for controlling said printing portion, a powersaving mode for stopping a supply of a power source to at least saidcontrolling portion, a deciding portion for deciding a shift from anormal mode to the power saving mode; a setting portion for settingcommunication control information used in the shift from the powersaving mode to the normal mode after the shift to the power saving modeis decided by said deciding portion; and a receiving portion forreceiving data based on the communication control information set bysaid setting portion in the shift from the power saving mode to thenormal mode not to use said controlling portion.
 2. The printing systemaccording to claim 1, connected to an upper system via a serial bus,wherein said receiving portion decides whether or not information isdirected to own system, by referring an address area in a packet, andresponds to only the information addressed to own system when theinformation is transmitted from the upper system via serialcommunication.
 3. The printing system according to claim 1, connected toan upper system via a parallel bus, wherein said deciding portiondecides a mode shift by detecting change of an input control signal of aparallel interface.
 4. A printing system comprising: a printing portion,a controlling portion for controlling said printing portion, a powersaving mode for stopping a supply of a power source to at least saidcontrolling portion, storing portion for storing received data; decidingportion for deciding a receiving speed based on a returning time fromthe power saving mode to a normal mode and a capacity of said storingportion; and receiving portion for receiving data based on the receivingspeed decided by said deciding portion in a shift from the power savingmode to the normal mode to store the data in said storing portion. 5.The printing system according to claim 4, wherein said deciding portiondecides dynamically the receiving speed in view of a residual capacityof said storing portion.
 6. The printing system according to claim 4,connected to an upper system via a serial bus, wherein said decidingportion decides the receiving speed based on setting of a data payloadin a packet in receiving serial data from the upper system.
 7. Theprinting system according to claim 4, connected to an upper system via aserial bus, wherein said deciding portion decides the receiving speedbased on a rate of notices informing that reception is normallycompleted, and notices informing that the reception is not normallycompleted, in replying a receiving response to the upper system.
 8. Theprinting system according to claim 4, connected to an upper system via aparallel bus, wherein said deciding portion decides a mode shift bydetecting a change of an input control signal in a parallel interface.